The National Park Service needs to include Hanford's historic B Reactor in any plan for a Manhattan District National Historic Park, nine members of the Washington congressional delegation said in a letter to the Park Service director.

The letter was signed by Sens. Patty Murray and Maria Cantwell, both D-Wash. Washington representatives who signed the letter included Republicans Doc Hastings, Cathy McMorris Rodgers and Dave Reichert and Democrats Norm Dicks, Adam Smith, Jay Inslee and Rick Larsen. In January, Hastings separately sent a similar letter to Park Service Director Jon Jarvis.

The Park Service has released a draft study of historical sites of the Manhattan Project, but "none of the draft alternatives as written fully provide for the preservation and interpretation of Hanford's B Reactor," the members' letter said.

Only some facilities in Los Alamos, N.M., initially including the homes of Manhattan Project scientists, are considered in the draft study for inclusion in a national park.

"We believe that the most unique and historically compelling technical facilities at all of the sites under consideration must be incorporated into any final National Park Service plan," the letter said.

B Reactor was the world's first full-scale nuclear reactor. Built in about 13 months, it produced the plutonium for the world's first atomic explosion and the bomb dropped on Nagasaki, Japan, helping end World War II. It continued to produce plutonium during the Cold War, along with other reactors based on its design.

The draft study eliminated B Reactor from consideration for a national park based on what Hastings earlier called "vague assertions and conclusions." Also eliminated were technical facilities at the Oak Ridge, Tenn., nuclear site.

The Park Service found there were questions of public access, safety, site ownership and financial liability.

However, supporters of preserving B Reactor as a museum have pointed out it already is open for public tours periodically and that DOE would continue to own the reactor.

"Many of us have had the opportunity to tour B Reactor, and the experience provides a very real sense of what it would have been like at Hanford in the 1940s," the letter said.

There is high interest in the limited tours that have been offered in recent years, with some tours filling within minutes of registration being announced, the letter said.

Registration for tours this year will open March 16, and B Reactor will be included on Hanford sitewide tours with registration opening Tuesday. Information for internet registration is posted at www.hanford.gov.

B Reactor "played an indelible role in our nation's history," the letter said.

"The preservation of this history will enable us, as a society, to have the opportunity to reflect and learn the important lessons that the B Reactor has to offer," it said.

The final Park Service report on Manhattan Project historical sites will be submitted to Congress for a decision on B Reactor's future.